The invention generally relates to the hydroformylation of unsaturated organic compounds utilizing supported bis(phosphorus) ligands. In particular, the invention relates to the hydroformylation of olefins utilizing supported bis(phosphorus) ligands.
Phosphorus ligands are ubiquitous in catalysis, finding use for a number of commercially important chemical transformations. Phosphorus ligands commonly encountered in catalysis include phosphines (A), and phosphites (B), shown below. In these representations R can be virtually any organic group. Monophosphine and monophosphite ligands are compounds which contain a single phosphorus atom which serves as a donor to a metal. Bisphosphine, bisphosphite, and bis(phosphorus) ligands in general, contain two phosphorus donor atoms and normally form cyclic chelate structures with transition metals. 
Two industrially important catalytic reactions using phosphorus ligands of particular importance are olefin hydrocyanation and olefin hydroformylation. Phosphite ligands are particularly good ligands for both of these transformations. For example, the hydrocyanation of ethylenically unsaturated compounds using transition metal complexes with monodentate phosphite ligands is well documented in the prior art. See, for example, U.S. Pat. Nos. 3,496,215, 3,631,191, 3,655,723 and 3,766,237, and Tolman et al., Advances in Catalysis, 33, 1, 1985. Bidentate bisphosphite ligands have been shown to be useful in the hydrocyanation of monoolefinic and diolefinic compounds, as well as for the isomerization of non-conjugated 2-alkyl-3-monoalkenenitriles to 3- and/or 4-monoalkene linear nitrites. See, for example, U.S. Pat. Nos. 5,512,695, 5,512,696 and WO 9514659. Bidentate phosphite ligands have also been shown to be particularly useful ligands in the hydrocyanation of activated ethylenically unsaturated compounds. See, for example, Baker, M. J., and Pringle, P. G., J. Chem. Soc., Chem. Commun., 1292, 1991; Baker et al., J. Chem. Soc., Chem. Commun., 803, 1991; WO 93,03839. Bidentate phosphite ligands are also useful for alkene hydroformylation reactions. For example, U.S. Pat. No. 5,235,113 describes a hydroformylation process in which an organic bidentate ligand containing two phosphorus atoms linked with an organic dihydroxyl bridging group is used in a homogeneous hydroformylation catalyst system also comprising rhodium. This patent describes a process for preparing aldehydes by hydroformylation of alkenically unsaturated organic compounds, for example 1-octene or dimerized butadiene, using the above catalyst system. Also, phosphite ligands have been disclosed with rhodium in the hydroformylation of functionalized ethylenically unsaturated compounds: Cuny et al., J. Am. Chem. Soc., 1993, 115, 2066. These prior art examples demonstrate the utility of bisphosphite ligands in catalysis.
While these prior art systems represent commercially viable catalysts, they do suffer from significant drawbacks. Primarily, the catalyst, consisting of the ligand and the metal, must be separated from the reaction products. Typically this is done by removing the product and catalyst mixture from the reaction zone and performing a separation. Typical separation procedures involve extraction with an immiscible solvent, distillation, and phase separations. In all of these examples some of the catalyst, consisting of the ligand and/or the metal, is lost. For instance, distillation of a volatile product from a non-volatile catalyst results in thermal degradation of the catalyst. Similarly, extraction or phase separation results in some loss of catalyst into the product phase. These ligands and metals are often very expensive and thus it is important to keep such losses to a minimum for a commercially viable process.
One method to solve the problem of catalyst and product separation is to attach the catalyst to an insoluble support. Examples of this approach have been previously described, and general references on this subject can be found in xe2x80x9cSupported Metal Complexesxe2x80x9d, D. Reidel Publishing, 1985, Acta Polymer. 1996, 47, 1, and Comprehensive Organometallic Chemistry, Pergamon Press, 1982, Chapter 55. Specifically, monophosphine and monophosphite ligands attached to solid supports are described in these references and also in Macromol. Symp. 1994, 80, 241. Bisphosphine ligands have also been attached to solid supports and used for catalysis, as described in for example U.S. Pat. No. 5,432,289, J. Mol. Catal. A 1996, 112, 217, and J. Chem. Soc., Chem. Commun. 1996, 653. The solid support in these prior art examples can be organic, e.g., a polymer resin, or inorganic in nature.
Commonly assigned copending provisional application Ser. No. 60/054,003, filed Jul. 29, 1997, overcomes many of the problems associated with catalytic hydrocyanation by utilizing supported bis(phosphorus) ligands coordinated to nickel for hydrocyanation of olefins.
These prior art systems have to date suffered from several drawbacks and have not reached commercial potential. Among the drawbacks noted in the literature are metal leaching and poor reaction rates. In addition, the prior art systems are often not readily amenable to precise control of the ligand coordination properties, e.g., electronics and steric size. What is needed is a supported bis(phosphorus) ligand system which overcomes the problems and deficiencies inherent in the prior art with respect to hydroformlyation. Other objects and advantages of the present invention will become apparent to those skilled in the art upon reference to the detailed description which hereinafter follows.
The present invention provides for the hydroformylation of olefins utilizing supported diols and chelating bis(phosphorus) ligands covalently bonded to a support. Preferably, the support is an insoluble polymer such as a crosslinked polystyrene resin or other organic polymer resin.
The supported bis(phosphorus) ligand has the structure (2): 
wherein:
Q is any organic fragment which binds a OPX2 moiety to the support (Sup); and
X is an alkoxy, aryloxy, alkyl, or aryl.
Preferably, X is aryloxide or aryl.
The supported catalyst composition has the structure (3): 
wherein:
Q is any organic fragment which binds a OPX2 moiety to the support (Sup);
X is an alkoxy, aryloxy, alkyl or aryl; and
M is a transition metal capable of carrying out catalytic transformations.
X is preferably aryloxide or aryl and M is preferably Ni, Rh, Co, Ir, Pd, Pt or Ru.
In particular, the invention provides for a hydroformylation process comprising reacting an acyclic, monoethylenically unsaturated compound with CO and H2 in the presence of a supported catalyst composition according to formula (3): 
wherein:
Q is any organic fragment which binds a OPX2 moiety to the support (Sup);
X is an alkoxy, aryloxy, alkyl or aryl; and
M is selected from the group consisting of rhodium and iridium
The invention further provides for the hydroformylation of aromatic olefins comprising reacting an acyclic aromatic olefin compound with CO and H2 in the presence of a supported catalyst composition according to formula (3): 
wherein:
Q is any organic fragment which binds a OPX2 moiety to the support (Sup);
X is an alkoxy, aryloxy, alkyl or aryl; and
M is rhodium.
This process may be run in either the liquid or vapor phase.
Also disclosed is a process for the preparation of a supported rhodium bisphosphite hydroformylation catalyst comprising reacting CO and H2 with a rhodium compound in the presence of a supported bis(phosphorus) ligand of formula 1 
in which Q is any organic fragment which binds the two phosphorus moieties to the support and X is alkoxy, aryloxy, alkyl, or aryl, or alternatively wherein the PX2 moiety forms a ring and X2 is a di(alkoxy), di(aryloxy), di(alkyl), or di(aryl). In a preferred embodiment, the supported ligand of Formula (1) is further characterized according to Formula (4) 
wherein:
the linker Q is a 2,2xe2x80x2-dihydroxyl-1,1xe2x80x2-binaphthalene bridging group;
the substituents R7 and R8 in the 3,3xe2x80x2 positions of the binaphthalene bridging group are selected from alkyl group containing 2 to 10 carbon atoms, an aryl group, an alkoxy group, an aryloxy group, a carboalkoxy group, a carboaryloxy group, a nitrile group, a triarylsilyl group, or trialkylsilyl group;
at least one of the groups R7 and R8 are covalently attached to a support (Sup);
X is an alkoxy, aryloxy, alkyl, or aryl, or alternatively the PX2 moiety forms a ring and X2 is a di(alkoxy), di(aryloxy), di(alkyl), or di(aryl).
A primary aim of this invention is to provide an improved hydroformylation reaction utilizing the catalysts covalently attached to an insoluble support, described in copending commonly assigned provisional application Ser. No. 60/054,003, filed Jul. 29, 1997. The advantages of this process are:
These catalysts are insoluble and non-volatile, allowing ready separation from the reaction medium by filtration or other means, or use in fixed bed, flow-through reactors using either liquid or gas phase carrier streams.
The chelating arrangement of donor atoms gives catalysts with commercially practical activity and selectivity. In particular, the chelates described herein are based on bisphosphite ligands, in which it is known that soluble derivatives give catalysts with significantly improved reaction rates and selectivities over monophosphite ligands.
The chelating arrangement of donor atoms results in a much stronger ligand-metal interaction and thus greatly minimizes the potential for metal leaching.
It is possible to methodically alter the spacing between the chelating atoms, the steric environment of these atoms, and the electronic properties of the donor atoms, thereby offering precise control of ligand coordination properties; this in turn allows significant opportunity to optimize catalyst performance.
The chemical environment in the immediate vicinity of the catalytically active site is uniform throughout the solid support matrix. The catalyst therefore acts as a xe2x80x9csingle sitexe2x80x9d type of catalyst, as opposed to an ensemble of different catalysts.
The supported bis(phosphorus) ligands described herein generally form the catalyst when combined with a catalytically active metal. The resulting supported catalyst forms a separate phase from the reaction medium, reacting substrates, and products. The reaction medium may be composed of a liquid solvent which does not interfere with the catalytic reaction of interest, or may be gaseous, e.g., an inert carrier gas and gaseous reactants and products.
Virtually any solid material may be used as a support in the context of this invention as long as it meets the following criteria:
The material is insoluble in organic, aqueous, or inorganic solvents. Organic polymer supports are acceptable in this regard but they generally need to be crosslinked. Inorganic supports, such as metal oxides (silicas, etc.) are generally insoluble in these solvents and also may be used as supports.
The support contains reactive sites which can be used for the covalent attachment of organic fragments containing a diol group (as described below) or a protected diol group.
The reactive sites are isolated to prevent additional crosslinking during further chemical transformations.
The reactive sites are exposed to the reaction medium. With a polymer resin support this is achieved through the use of resins which swell in a reaction solvent or is sufficiently porous to allow transport of the reaction medium through the polymer matrix.
The term xe2x80x9csolid supportxe2x80x9d or xe2x80x9csupportxe2x80x9d (sup) refers to a material having a rigid or semi-rigid surface which contain or can be derivatized to contain functionality which covalently links a compound to the surface thereof. Such materials are well known in the art and include, by way of example, polystyrene supports, polyacrylamide supports, polyethyleneglycol supports, metal oxides such as silica, and the like. Such supports will preferably take the form of small beads, pellets, disks, or other conventional forms, although other forms may be used.
The supports described in this application are functionalized poly(styrene) resins. Other suitable polymers include polyolefins, polyacrylates, polymethacrylates, and copolymers thereof that meet the general criteria described above. Specifically, poly(styrene) resins commonly used for solid phase synthesis have been used. These particular resins are crosslinked with from I to 10 wt % divinylbenzene. The styrene moieties are substituted in the para or meta positions. Only a portion of the styrene moieties are substituted, typically resulting in functional group loadings of approximately 0.2 to 2.0 mmole per gram of resin, although this value may be higher or lower.
The aims of this invention are achieved by construction of a chelating ligand covalently bonded to an insoluble support (Sup), preferably a polymer support (Pol). The first step of this procedure involves the preparation of a diol group covalently attached to an insoluble support as exemplified by the following structure: 
wherein, Sup represents the insoluble support. As used herein, Q means any organic fragment which binds the diol moiety to the support. For example, Q may consist of from 2 to 50 carbon atoms, in addition to heteroatoms such as nitrogen, oxygen, and the like. Q may additionally contain functional groups such as ether, acetal, ketal, ester, amide, amine, imine, etc., and combinations thereof. Q may also contain saturated or unsaturated carbon-carbon bonds. Q may or may not be symmetrical.
The number of atoms present in Q and used to separate the two OH moieties of the diol is generally limited to between 2 and 10, although any number and arrangement which ultimately allows the formation of a chelating ring is acceptable. A preferred number is 2 to 5 atoms. These atoms may be carbon or heteratoms such as oxygen and nitrogen. The atoms may further comprise a chain or cyclic structure, the latter of which may be saturated or unsaturated, e.g., aromatic.
The preparation of materials of Formula 1 follows methods known to those skilled in the art. The procedure may involve one reaction step or multiple reaction steps. Preferred methods are those which proceed in high yield, high selectivity, are inexpensive, and are simple to conduct. For example, Can. J. Chem. 1973, 51, 3756, describes the synthesis of the material of formula SD6. The synthesis occurs in two reaction steps from inexpensive materials and in high yield. Other materials described in this invention have not been previously reported in the literature but follow reaction steps known for soluble, non-polymer supported analogues. For instance, reaction of the polymer-supported benzaldehyde pol-CHO, prepared by the method described in J. Polym. Sci.1975, 13, 1951 and J. Polym. Sci., Polym. Lett. 1965, 3, 505, with pentaerythritol gives polymer-supported diol SD1. The analogous reaction of soluble, non-polymer supported benzaldehyde with pentaerythritol is described in Org. Syn. Vol 38, 65. Alternatively, reaction of polymer-supported aldehyde pol-CHO with diethyl tartrate, followed by reduction, leads to the class of polymer-supported diols SD2, 3, 4. SD3 is described in J. Org. Chem., 1997, 62, 3126. The analogous reactions of the soluble, non-polymer supported compounds are described in Helv. Chim. Acta 1983, 66, 2308 and J. Org. Chem. 1993, 58, 6182. Supported alkylene-bridged bisaryl alcohols can be prepared by methods found in J. Chem. Soc., Perkin I, 1980, 1978-1985; Indian J. Chem. 1995, 34B, 6-11, and Chem. Ber. 1985,118, 3588-3619. Other examples may be prepared by known organic transformations, and representative structures are shown below. 
The polymer-supported bis(phosphorus) ligands may be prepared by a variety of methods known in the art, for example, see descriptions in WO 93,03839; U.S. Pat. Nos. 4,769,498 and 4,668,651. In general, the transformation involves the reaction of a phosphorus halide, typically but not limited to chloride, with the diol to form P-O bonds. The phosphorus halide may be any compound of the type PYnX3xe2x88x92n, where Y=halide, X=alkoxide, aryloxide, alkyl, aryl, and n=3, 2, or 1. The phosphorus halides most useful for the present invention are those where Y=Cl; X=alkoxide, aryloxide, alkyl, or aryl; and n=1. The group X may contain from 1 to 50 carbon atoms. It may also optionally contain heteroatoms such as oxygen, nitrogen, halogen, and the like, and also functional groups such as ethers, alcohols, esters, amides, as well as others. The groups X may or may not be linked to form a cyclic structure. The PX2 moiety may form a ring and X2 may be a di(alkoxide), di(aryloxide), di(alkyl) or di(aryl). Many dialkylchlorophosphines and diarylchlorophosphines are commercially available, or may be prepared by methods known in the art, for example, J. Am. Chem. Soc. 1994, 116, 9869. Phosphorochloridites, may be prepared by a variety of methods known in the art, for example, see descriptions in Polymer 1992, 33, 161; Inorg. Syn. 1966, 8, 68; U.S. Pat. No. 5,210,260; Z. Anorg. Allg. Chem. 1986, 535, 221. For example, the reaction of 2,2xe2x80x2-biphenol with phosphorus trichloride gives 1,1xe2x80x2-biphenyl-2,2xe2x80x2-diylphosphorochloridite.
The reaction of these chlorophosphorus reagents with a material of Formula 1 in the presence of a base gives a polymer-supported bis(phosphorus) ligand exemplified by the structure shown: 
where X and Q are as defined above. Other examples may be prepared by similar transformations, and representative structures are also shown below. 
The transition metal catalysts which are a subject of this invention are defined by the formula shown below: 
wherein Q and X are as defined above. M is a transition metal capable of carrying out catalytic transformations. M may additionally contain labile ligands which are either displaced during the catalytic reaction, or take an active part in the catalytic transformation. Any of the transition metals may be considered in this regard. The preferred metals are those comprising groups 8, 9, and 10 of the Periodic Table. The preferred metals for hydroformylation are rhodium, cobalt, iridium, palladium and platinum, the most preferred being rhodium.
The zero-valent rhodium compounds, suitable for hydroformylation, can be prepared or generated according to techniques well known in the art, as described, for example, WO 95 30680, U.S. Pat. No. 3,907,847, and J. Amer. Chem. Soc., 115, 2066, 1993. Zero-valent rhodium compounds that contain ligands which can be displaced by the organophosporus ligands are a preferred source of zero-valent rhodium. Examples of such preferred zero-valent rhodium compounds are Rh(CO)2 (acetylacetonate) and Rh(CO)2(C4H9COCHCO-t-C4H9), Rh2O3, Rh4(CO)12, Rh6(CO)16, Rh(O2CCH3)2, and Rh(2-ethylhexanoate). Rhodium supported on carbon may also be used in this respect.
The present invention also provides a process for hydroformylation, comprising reacting an acyclic, monoethylenically unsaturated compound with a source of CO and H2 in the presence of a catalyst composition formed by the supported rhodium catalysts described previously and depicted by Formula 3.
Representative ethylenically unsaturated compounds which are useful in the process of this invention are shown in Formula I, III or V, and the corresponding terminal aldehyde compounds produced are illustrated by Formula II, IV or VI, respectively, wherein like reference characters have same meaning. 
wherein
R4 is H, CN, CO2R5, or perfluoroalkyl;
y is an integer of 0 to 12;
x is an integer of 0 to 12 when R4 is H, CO2R5 or perfluoroalkyl;
x is an integer of 1 to 12 when R4 is CN; and
R5 is alkyl. 
R6 is an alkyl, aryl, aralkyl, alkaryl, or fused aromatic group of up to 20 carbon atoms; R6 may further be branched or linear; R6 may also contain heteroatoms such as O, N, and F.
The nonconjugated acyclic, aliphatic, monoolefinically unsaturated starting materials useful in this invention include unsaturated organic compounds containing from 2 to approximately 30 carbon atoms. The monoolefins propylene, 1-butene, 2-butene, methyl 3-pentenoate, methyl 4-pentenoate, 3-pentenenitrile, and 4-pentenenitrile are especially preferred. As a practical matter, when the nonconjugated acyclic aliphatic monoethylenically unsaturated compounds are used in accordance with this invention, up to about 10% by weight of the monoethylenically unsaturated compound may be present in the form of a conjugated isomer, which itself may undergo hydroformylation. As used herein, the term xe2x80x9cpentenenitrilexe2x80x9d is intended to be identical with xe2x80x9ccyanobutenexe2x80x9d. Suitable unsaturated compounds include unsubstituted hydrocarbons as well as hydrocarbons substituted with groups which do not attack the catalyst, such as cyano. These unsaturated compounds include monoethylenically unsaturated compounds containing from 2 to 30 carbons such as ethylene, propylene, butene-1, pentene-2, hexene-2, etc.; nonconjugated diethylenically unsaturated compounds such as allene; and substituted compounds such as 3-pentenenitrile, 4-pentenenitrile, methyl pent-3-enoate; and ethylenically unsaturated compounds having perfluoroalkyl substituents such as, for example, CzF2z+1, where z is an integer of up to 20. The monoethylenically unsaturated compounds may also be conjugated to an ester group such as methyl pent-2-enoate.
Preferred are nonconjugated linear alkenes, nonconjugated linear alkenenitriles, nonconjugated linear alkenoates, linear alk-2-enoates and perfluoroalkyl ethylenes. Most preferred substrates include 3- and 4-pentenenitrile, alkyl 2-, 3-, and 4-pentenoates, and CzF2z+1CHxe2x95x90CH2 (where z is 1 to 12).
The preferred products are terminal alkanealdehydes, linear dialdehyde alkylenes, linear aliphatic aldehyde esters, and 3-(perfluoroalkyl)propioaldehyde. Most preferred products are n-butyraldehyde, methyl 5-formylvalerate, 2-phenyl-propionaldehyde, and 5-cyanovaleraldehyde.
The reaction conditions of the hydroformylation process according to this invention are in general the same as used in a conventional process, described, for example, in U.S. Pat. No. 4,769,498, which is incorporated herein by reference and will be dependent on the particular starting ethylenically unsaturated organic compound. For example, the temperature can be from room temperature to 200xc2x0 C., preferably from 50-120xc2x0 C. The pressure may vary from atmospheric pressure to 20 MPa, preferably from 0.15 to 10 MPa and more preferably from 0.2 to 1 MPa. The pressure is, as a rule, equal to the combined hydrogen and carbon monoxide partial pressure. Extra inert gases may however be present. The molar ratio of hydrogen to carbon monoxide is generally between 10 to 1 and 1 to 10, preferably between 6 to 1 and 1 to 2.
The amount of rhodium compound is not specially limited, but is optionally selected so that favorable results can be obtained with respect to catalyst activity and economy. In general, the concentration of rhodium in the reaction medium is between 10 and 10,000 ppm and more preferably between 50-500 ppm, calculated as the free metal.
The molar ratio of multidentate phosphorus ligand to rhodium is not specially limited, but is optionally selected so that favorable results can be obtained with respect to catalyst activity and aldehyde selectivity. This ratio generally is from about 0.5 to 100 and preferably from 1 to 10 (moles of ligand to moles of metal).
The choice of solvent is not critical provided the solvent is not detrimental to catalyst, reactant and product. The solvent may be a mixture of reactants, such as the starting unsaturated compound, the aldehyde product and/or by-products. Suitable solvents include saturated hydrocarbons such as kerosene, mineral oil or cyclohexane, ethers such as diphenyl ether tetrahydrofuran or a polyglycol, ketones such as methyl ethyl ketone and cyclohexanone, nitrites such as methylglutaronitrile and benzonitrile, aromatics such as toluene, benzene and xylene, esters such as methyl valerate and caprolactone, dimethylformamide, and sulfones such as tetramethylenesulfone. The reaction may also be conducted with reactants and products in the gas phase.
Preferably, when a liquid reaction medium is used, the reaction mixture is agitated, such as by stirring or shaking.
For the vapor phase hydroformylation, the preferred temperature range is from about 50xc2x0 C. to about 180xc2x0 C., most preferably from 80xc2x0 C. to 130xc2x0 C. The temperature must be chosen so as to maintain all of the reactants and products in the vapor phase, but low enough to prevent deterioration of the catalyst. The particular preferred temperature depends somewhat on the catalyst being used, the olefinic compound being reacted and the desired reaction rate. The operating pressure is not particularly critical and can conveniently be from about 101.3 to 1013 kPa. The pressure and temperature combination must be chosen so that all reactants and products remain in the vapor phase.
The supported rhodium catalysts of Formula 3 are typically loaded into tubular reactors, and a gaseous olefinic compound, e.g., propylene, CO, and H2 is passed continuously over the solid catalysts at temperatures sufficiently high to maintain the starting materials as well as the reaction products in the vapor phase.
Carbon monoxide, H2 and/or the olefinic starting materials can be delivered as a neat vapor or as a preheated solution in a solvent, such as acetonitrile or toluene. Under atmospheric pressure, using nitrogen or other inert gas as carrier. Nitrogen is preferred because of its low cost. The reaction products are liquid at room temperature and are conveniently recovered by cooling.